Throughout the specification, a unit of a network is used as a term including a cell unit network. Therefore, searching network may include the meaning of searching cells throughout the specification.
A wireless communication terminal according to the related art includes a hardware module and a software module having transceiving functions corresponding to a supported wireless communication scheme. In order to use a plurality of networks using different communication schemes with one wireless communication terminal, a dual mode or a multiple mode wireless communication terminal was introduced. Such a multiple mode wireless communication terminal includes a plurality of hardware modules and software modules corresponding to wireless communication schemes to support. Herein, a multiple mode service is performed by operating or not operating the hardware modules and software modules if it needs.
Such a multiple mode wireless communication terminal searches all of supportable wireless communication services or searches all of frequency bands in one communication mode, regularly or when a predetermined event such as location change occurs, in order to search networks.
In general, wireless communication terminals were designed to have a transceiving function to support only assigned wireless communication scheme in a hardware manner. Therefore, it is impossible to enable the wireless communication terminal to support newly introduced wireless communication scheme.
In order to overcome such a shortcoming of the wireless communication terminal, a software-defined radio (SDR) technology or a software radio were introduced. An SDR terminal can support various wireless communication schemes. In order to support various wireless communication schemes, the SDR terminal includes a reconfigurable hardware platform that enables wireless transceiving executable codes to be changed in software manner. Such an SDR terminal needs a new method for searching accessible networks because a supportable wireless communication scheme is not included in a hardware module or a software module unlike the wireless communication terminal according to the related art.
A network search method for an SDR terminal was introduced in U.S. Pat. No. 6,937,877 B2, entitled “Wireless Communication with a Mobile Asset Employing Dynamic Configuration of a Software Defined Radio.” In the method, the location information of an SDR terminal is obtained, a list of accessible networks is determined based on location information and the accessible network information, a network is selected from the list, and an SDR terminal is reconfigured with the selected network.
However, such a network search method has a shortcoming that cannot enable an SDR terminal to select a wireless network that provides the best quality in a view of signal strength or bandwidth because an SDR terminal did not consider a real receiving state in a peripheral radio wave environment.